Exergy Anaylsis on a refrigeration System

[Geminiman7]

I am trying to conduct exergetic anaylsis on a refrigeration system,below is my code

# -*- coding: utf-8 -*-
"""
Created on Tue Oct 15 14:05:35 2024
@author: ENGR. OGBORU REWARD
"""
import tespy
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
from tespy.networks import Network
from tespy.components import Sink, Source, Pump,SimpleHeatExchanger, Valve, Compressor, CycleCloser
from tespy.connections import Connection, Bus
from tespy.tools.characteristics import CharLine
from tespy.tools.characteristics import load_default_char as ldc



# Define the working fluid (choose either R134a or R404A)
fluid_list = ['R134a']  # or ['R404A'] if that’s what you meant to use

# Network setup
network = Network(fluids=fluid_list, T_unit='C', p_unit='bar', h_unit='J / kg', m_unit='kg / s')

# Define components
evaporator = SimpleHeatExchanger('Evaporator')
condenser = SimpleHeatExchanger('Condenser')
expansion_valve = Valve('Expansion Valve')
compressor = Compressor('Compressor')
cycle_closer = CycleCloser('Cycle Closer')  # Cycle closer to close the refrigerant loop

# Connecting components together
connection_cycle_closer_compressor = Connection(cycle_closer, 'out1', compressor, 'in1')
connection_compressor_condenser = Connection(compressor, 'out1', condenser, 'in1')
connection_condenser_expansion_valve = Connection(condenser, 'out1', expansion_valve, 'in1')
connection_expansion_valve_evaporator = Connection(expansion_valve, 'out1', evaporator, 'in1')
connection_evaporator_cycle_closer = Connection(evaporator, 'out1', cycle_closer, 'in1')

# Add connections to the network
network.add_conns(
    connection_cycle_closer_compressor, connection_compressor_condenser, 
    connection_condenser_expansion_valve, connection_expansion_valve_evaporator, 
    connection_evaporator_cycle_closer
)

# Define component attributes
compressor.set_attr(eta_s=0.78)  # Compressor efficiency

# Condenser and evaporator parameters
condenser.set_attr(pr=0.95, Q=-21142200)  # Example heat transfer for condenser
expansion_valve.set_attr(pr=0.6)  # Pressure drop through expansion valve
evaporator.set_attr(pr=0.8, Q=21142200)  # Example heat transfer for evaporator

# Set the initial conditions for the network
connection_cycle_closer_compressor.set_attr(T=-15, p=1.82, fluid={'R134a': 1})  # Adjusted to SI units

# Solve the network
network.solve('design')
network.print_results()

# Reference state for exergy analysis
T0 = 298.15  # Reference temperature (K)
p0 = 1.013e5  # Reference pressure (Pa)

# Exergy calculations for each connection
def calculate_exergy(connection, T0, p0):
    h = connection.h.val_SI  # Enthalpy (J/kg)
    s = connection.s.val_SI  # Entropy (J/(kg K))
    exergy = (h - 0) - T0 * (s - 0)  # Simplified exergy calculation
    print(f'Exergy at connection {connection.label}: {exergy} J/kg')
    return exergy

# Calculate exergy at each connection
calculate_exergy(connection_cycle_closer_compressor, T0, p0)
calculate_exergy(connection_compressor_condenser, T0, p0)
calculate_exergy(connection_condenser_expansion_valve, T0, p0)
calculate_exergy(connection_expansion_valve_evaporator, T0, p0)
calculate_exergy(connection_evaporator_cycle_closer, T0, p0)

[fwitte]

Hi @Geminiman7,

could you please give a little more context to your problem, what you already tried and where you have trouble to continue? Otherwise it is not really incentivizing to give advice here. A flow sheet of your system, a table of the boundary conditions that should be met etc.. That would also help you to build the model in a structured way, there are some inputs that are not reasonable at all (e.g. same amount of heat transfer on condenser and evaporator side).

Best

Francesco